3.5 V6 cam/valve cover randomly cracking

Ok...here's a new one.

Who's ever had their cam cover on their 3.5 randomly crack and start leaking oil?

I smelled hot oil, and saw smoke......then noticed the passenger side of the cross member was wet, and oil was on the exhaust.

I swear it looks like it was hit from the inside, but I have no clue how that would be possible....the engine is running great.

Thank gosh I keep a stick of two part epoxy in my glovebox.... hopefully that holds until I can figure how and why this happened.

 

If something hit it, the piece would not be flush. Since it is next to a feature, it might just be a molding flaw.

 

Did you show it to dealer? maybe they can send it over to Toyota?

 

It's a '17 with 102k miles. No warranty anymore.

 

Update

The patch is holding quite well. Not leaking anymore. I've used this stuff to patch exhaust manifolds, so I'm confident it will hold up on the cam cover.

Next up, finding and pricing out a new cover.

 

Agree. Something came lose inside. Better open sooner than later

 

Wow thats crazy, good idea on keeping something to patch stuff up with in the truck, im gonna have to do the same. hope you find a part for not too much.

 

I have no clue what it would be though. If it was valvetrain, that would absolutely be causing a misfire.....and it's not. Its running like a sewing machine.

 

You could have accidentally damaged it while doing top end work on your ACIS failure?
https://www.tacomaworld.com/threads...ld-flap-failure-2gr-fks-second-update.793953/

 

That was a long time ago....I would think that it would have started leaking long before a week or so ago. That intake was actually super easy to take off...but, anything is possible. I could have wacked the cover with a ratchet or extension and cracked it and never even knew until now.

I would say it was a better chance I would have done that when I changed the plugs though. That's right in that area.

 

I only can think of a bolt from the cradle that got lose or something was left inside.

 

Yeah, I’d guess it was hit by you or someone when working on it,,, but we’ll never really know, anything can fail. Good you caught it though!
Maybe w those miles and your patch job, you find it’s not (or barely) leaking and falls on the priority list.

 

Well, I'm gonna run this patched cover for a bit. If something is loose internally, it will break that patch. I do NOT want to ruin a brand new $250 cover.

If nothing ever happens, then I'll eventually just replace it and take a look when I change it. I did think it looked like it might have been from inside....but like another person brought up, I was all over the top of that engine when I replaced the upper intake and changed the plugs as well. I could have very well wacked that cover with a ratchet or extension and inadvertently compromised it.

 

Ok, here's the inside of the right cylinder head. This is picture of a used head I found. You can see the valve cover bolt hole next to the casting hole, right where my cover was cracked. There's nothing there that could have cracked it...unless the cam had a failure, which is unlikely as it runs fine....or a rocker came loose from under the cam and valve, also highly unlikely due to the drivability issues it would cause. So I'm kinda stumped until I actually take it apart, or I actually did damage it myself and I never realized it...and it took a while for the crack spread to the point it leaked.

 

your call, but I think that’s a bad idea. I would be concerned about that piece, letting go or a bigger chunk coming loose on the highway in the middle of absolutely nowhere.

With that being said, your epoxy might hold that together for the next 50 years

 

Hard to say. It must have been a hell of a whack if you caused it.

 

Punched a hole in my drivers V/C with a prybar. Didn't take much.

 

Unfortunately that cover isn't a next day item, so it's gonna take a bit to get. By the time it arrives, I should know if it was just fatigue or something else.

 

It might still run fine on one exhaust valve....I'd pull the valve cover and have a look, at the very least.

 

Damn! That's almost in the exact same spot too, just in the opposite cover. That's crazy. Now I wonder if I did just accidentally wack it and put a hairline crack in it that spread.